Cxnhc o o chchac o oh



United States Patent 2(BETA CARBOXY, ALPHA- R BETA-TH'IOCAR- gQALKOXY-THIOLPROPIONAMIDO) BENZOTHI- OLES Edward B. Knott, Harrow, England, assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application April 30, 1952, Serial No. 285,301

Claims. (Cl. 260-305) This invention relates to improvements in the production of photographic images, especially images on paper supports prepared from silver halide emulsions, and to new chemical compounds.

Silver halide emulsions are frequently subject to image quently manifests itself as plumming or bronzing of the image.

I have now found, however, that compounds which lcan be represented by the following two general formu- 3 C OR (g N=bNnoo Home 0 0M and z score N b-NHCO (imbue 0 0M wherein R represents an alkyl group, such as methyl, ethyl, n-propyl, n-butyl, isobutyl, n-amyl, n-heptyl, noctyl, etc., M represents a hydrogen atom or an alkali metal atom, e. g. sodium, potassium, etc., and Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series, are not only effective anti-plumming agents but upon prolonged standing, develop no objectionable color and show no increase in desensitizing properties.

It is, therefore, an object of my invention to provide a means for preventing image degradation in an exposed silver halide emulsion. Still another object is to provide new chemical compounds. Another object is to provide methods for making these new compounds. Another object is to provide photographic silver halide emulsions containing these new compounds. Otheryobjects will become apparent from a consideration of the following examples and description.

Accordingly, I realize the above objects by providing the compounds represented by Formulas I and II above, which can be used to prevent undesirable image degrada tion in exposed silver halide emulsions. When any of the above compounds represented by Formulas I and II are incorporated in silver halide emulsions, these compounds are advantageously used in a gelatino-silverchloride emulsion or a silver chloride emulsion containing small amounts of bromide or iodide. Silver halide emulsions in which the carrier is polyvinyl alcohol or hydrolyzed cellulose acetate can also be used. When the compounds are incorporated in the emulsion, they should I be used in amounts from 2.5 to 25 grams per unit of silver halide formed from 1000 grams of silver nitrate. The same concentration of compounds should be present in the emulsion when the compounds are added'by bathing the emulsion in a solution containing them. When the emulsion layer is bathed in a solution of the compound, the solution can contain up to about 5 per cent by weight of the-compound.

According to my invention, I provide the new compounds represented by Formula I above by heating tomice gether a compound selected from those represented by the following general formula:

III ,z

bl b-NHcocn=oncooH wherein Z has the values given above, with an alkali metal salt selected from those represented by the following general formula:

IV E

ROCSM:

wherein R has the values given above and M1 represents a metal atom, such as an alkali metal atom, e. g. sodium, potassium, etc., and an amount of acidsufficient to liberate the free acid of the said alkali metal salt compound represented by Formula IV. Acids useful for this purpose comprise acetic acid, hydrochloric acid, sulfuric acid, etc., although it is to be understood that other acids can be used, since the purpose of the acid is simply to displace the metal atom of the compounds of Formula IV with a proton, i. e. a hydrogen atom.

The compounds represented by Formula III above can be prepared by condensing a compound selected from those represented by the following general formula:

I 'I b-Nrn wherein Z has the values given above, with maleic anhydride, such a process being described in my copending application Serial No. 285,302, filed on even date herewith. Typical aminobenzothiazole compounds included within the scope of Formula V above comprise, for example, the following: Z-aminobenzothiazole, 2- amino-5-bromobenzothiazole, Z-amino- 6 -,bromobenzothiazole, 2-amino-4- chlorobenzothiazole, 2 amino 6- chlorobenzothiazole, 2-amino-7-chloro-4 methoxybenzothiazole, 2-amino-4-methoxybenzothiazole, 2-amino-5- methoxybenzothiazole, 2 amino 6 methoxybenzothiazole, 2-amino-6-ethoxybenzothiazole, 2 amino 4- n-butoxybenzothiazole, 2 amino 6-isobutoxybenzothiazole, 2 amino 4 methylbenzothiazole, 2 amino 6- methylbenzothiazole, etc.

The compounds selected from those represented by Formula II above can advantageously be prepared by mixing together a compound selected from those represented by Formula III above with ammonia to produce the ammonium salt of the compound of Formula III and thereafter mixing the resulting ammonium salt together with an alkali metal salt selected from those represented by Formula III and a suflicient amount of acid to liberate the free acid of the compound of Formula IV, i. e., a sufficient amount of acid to give the reaction mixture a pH below 7. Acids which have been found useful for the purpose of liberating the free acid of the compound of Formula IV comprise, for example, acetic acid, hydrochloric acid, sulfuric acid, etc., although other acids can be used to equal advantage.

The following examples will serve to illustrate more fully the manner whereby I prepare the new compounds of my invention.

Example 1.-2-(B-carboxy-athiocarbomethoxythiolprw pionamido)benzothiazole 2.5 g. of the Z-aminobnzothiazole salt of Z-(B-carboxyacrylamido)benzothiazole, 1.65 g. of methoxydithioformate, and 10 cc. of acetic acid were heated together on a steam bath for 15 minutes. There was a slight eflervescence and the reactants dissolved. A white, crysuct. It was recrystallized from ethanol as colorless needl es, M. 1, 207 C. with decomposition.

Example 2.2-(,B-carb0xy-u-thiocarbethoxythiolpropion- 2.5 g. of 2 (/S-carboxyacrylami d o)benzothiazol, .2.7 g. of potassium ethoxydithioformate, and 10 cc. of acetic acid were heated together on the steambath forj5 minutes with stirring. The thick, white precipitate was slurried in cc. of ethanol and collected on a filter. The yield was 80 per cent. From acetic acid, the desired product formed opaque aggregates, M. .P. 205' C.

Example 3. 2(B-carboxrwthiocarboqz butoxythiolpropiqnamidolbenzothiazole Example 4.-2-(fl-carboxy-urthiocarbo-moctoxythiolprapionamido.) benzothia zole S S "H s 00 CaH11(n) 'C-NHC o 011011200011 \N 4.0 g. of the 2-aminobenzothiazole salt of ,2-(,B-,carboxyacrylamido)benzothiazole, ,-2.5 g. of potassium n-octoxydithioformate, and 15 cc. of acetic acid were heatedto- .gether on the steam bath for 10 minutes. The resulting .white precipitate was collected on a filter and washedwith ethanol. The yield of crude product was 2.5 3,, -55;pe r

cent, and had M. P. 190 C. on recrystallizationfrom ethanol, it formed fatty flakes, M. P. 192 C.

Example 5.-2-(fi-carboxy /Sflziocarbo-mbutoxythiolpropionamidolbenzothiazole s K 'n S C 0 CiHo(n) 2.5 g. of 2-(fl-carboxyacrylamido)benzothiazole were d ssolved m a solution of ammonia 2 cc.) having-aspecific gravity of 0.880 and water cc.). Potassium ,nbutonydithioformate (2.0 g.) was then dissolved in this solutlon at 20 C. With rapid stirring, 40 cc. of a 10 per ,cent solution of acetic acid was dripped in over a period of 2 minutes. A thick, pale yellow precipitate was formed and this was collected on a filter and washed with water. The y eld was 2.3 g., 57.5 per cent and had M. P. 232 C. (previous darkening). Onrecrystallization from ethanol, the desired product formed tiny, pale yellow needles, M. P. 233-235 C. (darkened at :about 198 0.).

Example 6. 6-eth0xy-2-(B-carboxy-a-thiocarbo-n-butoxythzolpropionamido ben zothiazale S CzHzO G-NQHC 0 .3. .1 20 O 0.3

'[N 4.8 g. of Z-(B-carboxyacrylamido)-6-ethoxybenzothioazole (as 1ts Z-ammo-G-ethoxybenzpthiazole 'salt), 2.0 of potassium n'-butoxydithiofor rnate, and 20 cc. of acetic acid were warmed on the steam bath for 5 minutes. The

"addition offitl ccuof'watcrtothe clear solution precipitated a tacky solid which slowly hardened. From ethanol, it formed a pale violet powder, M. P. 178 C. The yield was 2.5 g.

In addition to serving as. the liberating acid in the above examples, the acetic acid also acted as a solvent. Other 'diluents, such-as ethanol, 1,4-dioxane, etc., can be used "solongas suflicient acidis present to liberate the free alkoxydithioformic acid, which is necessary for the process of li y-invention. The product of Example II, for ex- ;.ample,"was obtained in .'similar,yield when the amount of acetic acid wasreduced to 1.0 cc. and 20 cc. of ethanol were used as the diluent.

I have-also foundthat the. new compounds of my invention can also be used'in the vulcanization of rubber.

What I claim as my invention and desired secured by Letters Patent. of the United States is:

1. A compound selected from the group consisting of .thoserepresented by. theiollowing'two general formulas:

S slloiorr. cqmooclromooon 3. The compoundf'having the, following formula:

5 is .slioctn.

fo-m1oobnomooon 4. compound'having the following formula:

fi S C O C4Hn(n) C-NHC 0 Home 0 OH N :5. The 'compound 'rhaving the following formula:

v s y '8 o 01mm C.N"HUO 03,0110 00H -'6. The compound having the following formula:

:s -.s go 0. mm

o-mrroo'onomoo'on 7. A process for preparing a compound selected from those represented by the following general formula:

if S 0 OR I N C-NHCO HCHZCOOH wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series selected from the group consisting of benzothiazole and benzothiazole having substituted thereon a radical selected from the group consisting of bromine, chlorine, methyl, and an alkoxyl group wherein the alkyl group is a primary alkyl group containing from 1-4 carbon atoms, and R represents an alkyl group containing from 1 to 8 carbon atoms, comprising heating together a compound ielectltleld from those represented by the following general orm a:

wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series selected from the group consisting of benzothiazole and benzothiazole having substituted thereon a radical selected from the group consisting of bromine, chlorine, methyl, and an alkoxyl group wherein the alkyl group is a primary alkyl group containing from 1-4 carbon atoms, an alkali metal salt selected from those represented by the following general formula:

i ROCSM! wherein R represents an alkyl group containing from 1 to 8 carbon atoms and M1 represents an alkali metal atom, and an amount of acid suflicient to liberate the free acid of the said alkali metal salt compound.

8. A process according to claim 7 wherein acetic acid is employed as the acid for liberating the free acid of the said alkali metal salt compound.

9. A process for preparing a compound selected from those represented by the following general formula:

i ,z. s COR 16 tJ-NHCOCHzCHCOOH wherein Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series selected from the group consisting of benzothiazole and benzothiazole having substituted thereon a radical selected from the group consisting of bromine, chlorine, methyl, and an alkoxyl group wherein the alkyl group is a primary alkyl group containing from l-4 carbon atoms, an alkali metal salt selected from those represented by the following general formula:

i ROOSMi wherein R represents an alkyl group containing from 1 to 8 carbon atoms and M1 represents an alkali metal atom, and a sufiicient amount of acid to give the mixture a pH below 7.

10. A process according to claim 9 wherein acetic acid is used as the acid to give the mixture a pH below 7.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Weissberger Apr. 11, 1950 Number 

1. A COMPOUND SELECTED FROM THE GROUP CONSISTING OF THOSE REPRESENTED BY THE FOLLOWING TWO GENERAL FORMULAS: 